QWindow Class

Windows can potentially use a lot of memory. A usual measurement is width times height times color depth. A window might also include multiple buffers to support double and triple buffering, as well as depth and stencil buffers. To release a window's memory resources, call the destroy() function.

QWindow has reportContentOrientationChange() that can be used to specify the layout of the window contents in relation to the screen. The content orientation is simply a hint to the windowing system about which orientation the window contents are in. It's useful when you wish to keep the same window size, but rotate the contents instead, especially when doing rotation animations between different orientations. The windowing system might use this value to determine the layout of system popups or dialogs.

By default, the window is not visible, and you must call setVisible(true), or show() or similar to make it visible. To make a window hidden again, call setVisible(false) or hide(). The visible property describes the state the application wants the window to be in. Depending on the underlying system, a visible window might still not be shown on the screen. It could, for instance, be covered by other opaque windows or moved outside the physical area of the screen. On windowing systems that have exposure notifications, the isExposed() accessor describes whether the window should be treated as directly visible on screen. The exposeEvent() function is called whenever an area of the window is invalidated, for example due to the exposure in the windowing system changing. On windowing systems that do not make this information visible to the application, isExposed() will simply return the same value as isVisible().

QWindow::Visibility queried through visibility() is a convenience API combining the functions of visible() and windowStates().

There are two Qt APIs that can be used to render content into a window, QBackingStore for rendering with a QPainter and flushing the contents to a window with type QSurface::RasterSurface, and QOpenGLContext for rendering with OpenGL to a window with type QSurface::OpenGLSurface.

The application can start rendering as soon as isExposed() returns true, and can keep rendering until it isExposed() returns false. To find out when isExposed() changes, reimplement exposeEvent(). The window will always get a resize event before the first expose event.

If the window's width and height are left uninitialized, the window will get a reasonable default geometry from the platform window. If the position is left uninitialized, then the platform window will allow the windowing system to position the window. For example on X11, the window manager usually does some kind of smart positioning to try to avoid having new windows completely obscure existing windows. However setGeometry() initializes both the position and the size, so if you want a fixed size but an automatic position, you should call resize() or setWidth() and setHeight() instead.

This enum is used to control whether or not transient parents should be considered ancestors.

This enum describes what part of the screen the window occupies or should occupy.

This enum was introduced or modified in Qt 5.1.

This property holds the active status of the window

This property was introduced in Qt 5.1.

Access functions:

• bool isActive() const

Notifier signal:

• void activeChanged()

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This property holds the orientation of the window's contents

This is a hint to the window manager in case it needs to display additional content like popups, dialogs, status bars, or similar in relation to the window.

The recommended orientation is QScreen::orientation() but an application doesn't have to support all possible orientations, and thus can opt to ignore the current screen orientation.

The difference between the window and the content orientation determines how much to rotate the content by. QScreen::angleBetween(), QScreen::transformBetween(), and QScreen::mapBetween() can be used to compute the necessary transform.

The default value is Qt::PrimaryOrientation

Access functions:

• contentOrientation() const

• void reportContentOrientationChange( orientation)

Notifier signal:

• void contentOrientationChanged( orientation)

This property holds the window flags of the window

The window flags control the window's appearance in the windowing system, whether it's a dialog, popup, or a regular window, and whether it should have a title bar, etc.

The actual window flags might differ from the flags set with setFlags() if the requested flags could not be fulfilled.

Access functions:

• flags() const

• void setFlags( flags)

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This property holds the height of the window's geometry

Access functions:

• int height() const

• void setHeight(int arg)

Notifier signal:

• void heightChanged(int arg)

This property holds the maximum height of the window's geometry

Access functions:

• int maximumHeight() const

• void setMaximumHeight(int h)

Notifier signal:

• void maximumHeightChanged(int arg)

This property holds the maximum width of the window's geometry

Access functions:

• int maximumWidth() const

• void setMaximumWidth(int w)

Notifier signal:

• void maximumWidthChanged(int arg)

This property holds the minimum height of the window's geometry

Access functions:

• int minimumHeight() const

• void setMinimumHeight(int h)

Notifier signal:

• void minimumHeightChanged(int arg)

This property holds the minimum width of the window's geometry

Access functions:

• int minimumWidth() const

• void setMinimumWidth(int w)

Notifier signal:

• void minimumWidthChanged(int arg)

This property holds the modality of the window

A modal window prevents other windows from receiving input events. Qt supports two types of modality: Qt::WindowModal and Qt::ApplicationModal.

By default, this property is Qt::NonModal

Access functions:

• modality() const

• void setModality( modality)

Notifier signal:

• void modalityChanged( modality)

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This property holds the opacity of the window in the windowing system.

If the windowing system supports window opacity, this can be used to fade the window in and out, or to make it semitransparent.

A value of 1.0 or above is treated as fully opaque, whereas a value of 0.0 or below is treated as fully transparent. Values inbetween represent varying levels of translucency between the two extremes.

The default value is 1.0.

This property was introduced in Qt 5.1.

Access functions:

• qreal opacity() const

• void setOpacity(qreal level)

Notifier signal:

• void opacityChanged(qreal opacity)

This property holds the window's title in the windowing system

The window title might appear in the title area of the window decorations, depending on the windowing system and the window flags. It might also be used by the windowing system to identify the window in other contexts, such as in the task switcher.

Access functions:

• title() const

• void setTitle(const QString &)

Notifier signal:

• void windowTitleChanged(const &title)

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This property holds the window for which this window is a transient pop-up

This is a hint to the window manager that this window is a dialog or pop-up on behalf of the transient parent.

In order to cause the window to be centered above its transient parent by default, depending on the window manager, it may also be necessary to call setFlags() with a suitable Qt::WindowType (such as Qt::Dialog).

This property was introduced in Qt 5.13.

Access functions:

• *transientParent() const

• void setTransientParent( *parent)

Notifier signal:

• void transientParentChanged( *transientParent)

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This property holds the screen-occupation state of the window

Visibility is whether the window should appear in the windowing system as normal, minimized, maximized, fullscreen or hidden.

To set the visibility to AutomaticVisibility means to give the window a default visible state, which might be fullscreen or windowed depending on the platform. When reading the visibility property you will always get the actual state, never AutomaticVisibility.

This property was introduced in Qt 5.1.

Access functions:

• visibility() const

• void setVisibility( v)

Notifier signal:

• void visibilityChanged( visibility)

This property holds whether the window is visible or not

This property controls the visibility of the window in the windowing system.

By default, the window is not visible, you must call setVisible(true), or show() or similar to make it visible.

Access functions:

• bool isVisible() const

• void setVisible(bool visible)

Notifier signal:

• void visibleChanged(bool arg)

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This property holds the width of the window's geometry

Access functions:

• int width() const

• void setWidth(int arg)

Notifier signal:

• void widthChanged(int arg)

This property holds the x position of the window's geometry

Access functions:

• int x() const

• void setX(int arg)

Notifier signal:

• void xChanged(int arg)

This property holds the y position of the window's geometry

Access functions:

• int y() const

• void setY(int arg)

Notifier signal:

• void yChanged(int arg)

Creates a window as a top level on the targetScreen.

The window is not shown until setVisible(true), show(), or similar is called.

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Creates a window as a child of the given parent window.

The window will be embedded inside the parent window, its coordinates relative to the parent.

The screen is inherited from the parent.

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Destroys the window.

Causes an alert to be shown for msec milliseconds. If msec is 0 (the default), then the alert is shown indefinitely until the window becomes active again. This function has no effect on an active window.

In alert state, the window indicates that it demands attention, for example by flashing or bouncing the taskbar entry.

This function was introduced in Qt 5.1.

Returns the base size of the window.

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Close the window.

This closes the window, effectively calling destroy(), and potentially quitting the application. Returns true on success, false if it has a parent window (in which case the top level window should be closed instead).

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Override this to handle close events (ev).

The function is called when the window is requested to close. Call QEvent::ignore() on the event if you want to prevent the window from being closed.

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Allocates the platform resources associated with the window.

It is at this point that the surface format set using setFormat() gets resolved into an actual native surface. However, the window remains hidden until setVisible() is called.

Note that it is not usually necessary to call this function directly, as it will be implicitly called by show(), setVisible(), and other functions that require access to the platform resources.

Call destroy() to free the platform resources if necessary.

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the cursor shape for this window

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Releases the native platform resources associated with this window.

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Returns the ratio between physical pixels and device-independent pixels for the window. This value is dependent on the screen the window is on, and may change when the window is moved.

Common values are 1.0 on normal displays and 2.0 on Apple "retina" displays.

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Reimplements: QObject::event(QEvent *e).

Override this to handle any event (ev) sent to the window. Return true if the event was recognized and processed.

Remember to call the base class version if you wish for mouse events, key events, resize events, etc to be dispatched as usual.

The expose event (ev) is sent by the window system when a window moves between the un-exposed and exposed states.

An exposed window is potentially visible to the user. If the window is moved off screen, is made totally obscured by another window, is minimized, or similar, this function might be called and the value of isExposed() might change to false. You may use this event to limit expensive operations such as animations to only run when the window is exposed.

This event should not be used to paint. To handle painting implement paintEvent() instead.

A resize event will always be sent before the expose event the first time a window is shown.

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the file name this window is representing.

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Override this to handle focus in events (ev).

Focus in events are sent when the window receives keyboard focus.

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Returns the QObject that will be the final receiver of events tied focus, such as key events.

This signal is emitted when the final receiver of events tied to focus is changed to object.

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Override this to handle focus out events (ev).

Focus out events are sent when the window loses keyboard focus.

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Reimplements: QSurface::format() const.

Returns the actual format of this window.

After the window has been created, this function will return the actual surface format of the window. It might differ from the requested format if the requested format could not be fulfilled by the platform. It might also be a superset, for example certain buffer sizes may be larger than requested.

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Returns the geometry of the window, including its window frame.

The geometry is in relation to the virtualGeometry() of its screen.

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Returns the window frame margins surrounding the window.

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Returns the top left position of the window, including its window frame.

This returns the same value as frameGeometry().topLeft().

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Creates a local representation of a window created by another process or by using native libraries below Qt.

Given the handle id to a native window, this method creates a QWindow object which can be used to represent the window when invoking methods like setParent() and setTransientParent().

This can be used, on platforms which support it, to embed a QWindow inside a native window, or to embed a native window inside a QWindow.

If foreign windows are not supported or embedding the native window failed in the platform plugin, this function returns nullptr.

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Returns the geometry of the window, excluding its window frame.

The geometry is in relation to the virtualGeometry() of its screen.

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Hides the window.

Equivalent to calling setVisible(false).

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Override this to handle hide events (ev).

The function is called when the window has requested being hidden in the windowing system.

Returns the window's icon in the windowing system

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Returns true if the window is active.

This is the case for the window that has input focus as well as windows that are in the same parent / transient parent chain as the focus window.

Typically active windows should appear active from a style perspective.

To get the window that currently has focus, use QGuiApplication::focusWindow().

Returns true if the window is an ancestor of the given child. If mode is IncludeTransients, then transient parents are also considered ancestors.

Returns if this window is exposed in the windowing system.

When the window is not exposed, it is shown by the application but it is still not showing in the windowing system, so the application should minimize animations and other graphical activities.

An exposeEvent() is sent every time this value changes.

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Returns whether the window is modal.

A modal window prevents other windows from getting any input.

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Returns whether the window is top level, i.e. has no parent window.

Override this to handle key press events (ev).

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Override this to handle key release events (ev).

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Lower the window in the windowing system.

Requests that the window be lowered to appear below other windows.

Translates the global screen coordinate pos to window coordinates.

This function was introduced in Qt 6.0.

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This is an overloaded function.

Translates the window coordinate pos to global screen coordinates. For example, mapToGlobal(QPointF(0,0)) would give the global coordinates of the top-left pixel of the window.

This function was introduced in Qt 6.0.

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This is an overloaded function.

Returns the mask set on the window.

The mask is a hint to the windowing system that the application does not want to receive mouse or touch input outside the given region.

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Returns the maximum size of the window.

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Returns the minimum size of the window.

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This signal is emitted when the Qwindow::modality property changes to modality.

Override this to handle mouse double click events (ev).

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Override this to handle mouse move events (ev).

Override this to handle mouse press events (ev).

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Override this to handle mouse release events (ev).

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Override this to handle window move events (ev).

Override this to handle platform dependent events. Will be given eventType, message and result.

This might make your application non-portable.

Should return true only if the event was handled.

The paint event (ev) is sent by the window system whenever an area of the window needs a repaint, for example when initially showing the window, or due to parts of the window being uncovered by moving another window.

The application is expected to render into the window in response to the paint event, regardless of the exposed state of the window. For example, a paint event may be sent before the window is exposed, to prepare it for showing to the user.

This function was introduced in Qt 6.0.

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Returns the parent window, if any.

If mode is IncludeTransients, then the transient parent is returned if there is no parent.

A window without a parent is known as a top level window.

This function was introduced in Qt 5.9.

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Returns the position of the window on the desktop excluding any window frame

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Raise the window in the windowing system.

Requests that the window be raised to appear above other windows.

Requests the window to be activated, i.e. receive keyboard focus.

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Schedules a QEvent::UpdateRequest event to be delivered to this window.

The event is delivered in sync with the display vsync on platforms where this is possible. Otherwise, the event is delivered after a delay of 5 ms. The additional time is there to give the event loop a bit of idle time to gather system events, and can be overridden using the QT_QPA_UPDATE_IDLE_TIME environment variable.

When driving animations, this function should be called once after drawing has completed. Calling this function multiple times will result in a single event being delivered to the window.

Subclasses of QWindow should reimplement event(), intercept the event and call the application's rendering code, then call the base class implementation.

This function was introduced in Qt 5.5.

Returns the requested surface format of this window.

If the requested format was not supported by the platform implementation, the requestedFormat will differ from the actual window format.

This is the value set with setFormat().

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set the size of the window, excluding any window frame, to newSize

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set the size of the window, excluding any window frame, to a QSize constructed from width w and height h

For interactively resizing windows, see startSystemResize().

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Override this to handle resize events (ev).

The resize event is called whenever the window is resized in the windowing system, either directly through the windowing system acknowledging a setGeometry() or resize() request, or indirectly through the user resizing the window manually.

Returns the screen on which the window is shown, or null if there is none.

For child windows, this returns the screen of the corresponding top level window.

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This signal is emitted when a window's screen changes, either by being set explicitly with setScreen(), or automatically when the window's screen is removed.

Sets the base size of the window.

The base size is used to calculate a proper window size if the window defines sizeIncrement().

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set the cursor shape for this window

The mouse cursor will assume this shape when it is over this window, unless an override cursor is set. See the list of predefined cursor objects for a range of useful shapes.

If no cursor has been set, or after a call to unsetCursor(), the parent window's cursor is used.

By default, the cursor has the Qt::ArrowCursor shape.

Some underlying window implementations will reset the cursor if it leaves a window even if the mouse is grabbed. If you want to have a cursor set for all windows, even when outside the window, consider QGuiApplication::setOverrideCursor().

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set the file name this window is representing.

The windowing system might use filePath to display the path of the document this window is representing in the tile bar.

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Sets the window flag flag on this window if on is true; otherwise clears the flag.

This function was introduced in Qt 5.9.

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Sets the window's surface format.

The format determines properties such as color depth, alpha, depth and stencil buffer size, etc. For example, to give a window a transparent background (provided that the window system supports compositing, and provided that other content in the window does not make it opaque again):

QSurfaceFormat format;
format.setAlphaBufferSize(8);
window.setFormat(format);

The surface format will be resolved in the create() function. Calling this function after create() has been called will not re-resolve the surface format of the native surface.

When the format is not explicitly set via this function, the format returned by QSurfaceFormat::defaultFormat() will be used. This means that when having multiple windows, individual calls to this function can be replaced by one single call to QSurfaceFormat::setDefaultFormat() before creating the first window.

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Sets the upper left position of the window (point) including its window frame.

The position is in relation to the virtualGeometry() of its screen.

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Sets the geometry of the window, excluding its window frame, to a rectangle constructed from posx, posy, w and h.

The geometry is in relation to the virtualGeometry() of its screen.

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Sets the geometry of the window, excluding its window frame, to rect.

The geometry is in relation to the virtualGeometry() of its screen.

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Sets the window's icon in the windowing system

The window icon might be used by the windowing system for example to decorate the window, and/or in the task switcher.

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Sets whether keyboard grab should be enabled or not (grab).

If the return value is true, the window receives all key events until setKeyboardGrabEnabled(false) is called; other windows get no key events at all. Mouse events are not affected. Use setMouseGrabEnabled() if you want to grab that.

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Sets the mask of the window.

The mask is a hint to the windowing system that the application does not want to receive mouse or touch input outside the given region.

The window manager may or may not choose to display any areas of the window not included in the mask, thus it is the application's responsibility to clear to transparent the areas that are not part of the mask.

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Sets the maximum size of the window.

This is a hint to the window manager to prevent resizing above the specified size.

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Sets the minimum size of the window.

This is a hint to the window manager to prevent resizing below the specified size.

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Sets whether mouse grab should be enabled or not (grab).

If the return value is true, the window receives all mouse events until setMouseGrabEnabled(false) is called; other windows get no mouse events at all. Keyboard events are not affected. Use setKeyboardGrabEnabled() if you want to grab that.

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Sets the parent Window. This will lead to the windowing system managing the clip of the window, so it will be clipped to the parent window.

Setting parent to be nullptr will make the window become a top level window.

If parent is a window created by fromWinId(), then the current window will be embedded inside parent, if the platform supports it.

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set the position of the window on the desktop to pt

The position is in relation to the virtualGeometry() of its screen.

For interactively moving windows, see startSystemMove(). For interactively resizing windows, see startSystemResize().

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set the position of the window on the desktop to posx, posy

The position is in relation to the virtualGeometry() of its screen.

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Sets the screen on which the window should be shown.

If the window has been created, it will be recreated on the newScreen.

This function only works for top level windows.

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Sets the size increment (size) of the window.

When the user resizes the window, the size will move in steps of sizeIncrement().width() pixels horizontally and sizeIncrement().height() pixels vertically, with baseSize() as the basis.

By default, this property contains a size with zero width and height.

The windowing system might not support size increments.

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Sets the surfaceType of the window.

Specifies whether the window is meant for raster rendering with QBackingStore, or OpenGL rendering with QOpenGLContext.

The surfaceType will be used when the native surface is created in the create() function. Calling this function after the native surface has been created requires calling destroy() and create() to release the old native surface and create a new one.

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Associates this window with the specified Vulkan instance.

instance must stay valid as long as this QWindow instance exists.

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set the screen-occupation state of the window

The window state represents whether the window appears in the windowing system as maximized, minimized, fullscreen, or normal.

The enum value Qt::WindowActive is not an accepted parameter.

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set the screen-occupation state of the window

The window state represents whether the window appears in the windowing system as maximized, minimized and/or fullscreen.

The window can be in a combination of several states. For example, if the window is both minimized and maximized, the window will appear minimized, but clicking on the task bar entry will restore it to the maximized state.

The enum value Qt::WindowActive should not be set.

This function was introduced in Qt 5.10.

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Shows the window.

This is equivalent to calling showFullScreen(), showMaximized(), or showNormal(), depending on the platform's default behavior for the window type and flags.

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Override this to handle show events (ev).

The function is called when the window has requested becoming visible.

If the window is successfully shown by the windowing system, this will be followed by a resize and an expose event.

Shows the window as fullscreen.

Equivalent to calling setWindowStates(Qt::WindowFullScreen) and then setVisible(true).

See the QWidget::showFullScreen() documentation for platform-specific considerations and limitations.

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Shows the window as maximized.

Equivalent to calling setWindowStates(Qt::WindowMaximized) and then setVisible(true).

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Shows the window as minimized.

Equivalent to calling setWindowStates(Qt::WindowMinimized) and then setVisible(true).

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Shows the window as normal, i.e. neither maximized, minimized, nor fullscreen.

Equivalent to calling setWindowStates(Qt::WindowNoState) and then setVisible(true).

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Reimplements: QSurface::size() const.

Returns the size of the window excluding any window frame

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Returns the size increment of the window.

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Start a system-specific move operation

Calling this will start an interactive move operation on the window by platforms that support it. The actual behavior may vary depending on the platform. Usually, it will make the window follow the mouse cursor until a mouse button is released.

On platforms that support it, this method of moving windows is preferred over setPosition, because it allows a more native look-and-feel of moving windows, e.g. letting the window manager snap this window against other windows, or special tiling or resizing behavior with animations when dragged to the edge of the screen. Furthermore, on some platforms such as Wayland, setPosition is not supported, so this is the only way the application can influence its position.

Returns true if the operation was supported by the system.

This function was introduced in Qt 5.15.

Start a system-specific resize operation

Calling this will start an interactive resize operation on the window by platforms that support it. The actual behavior may vary depending on the platform. Usually, it will make the window resize so that its edge follows the mouse cursor.

On platforms that support it, this method of resizing windows is preferred over setGeometry, because it allows a more native look and feel of resizing windows, e.g. letting the window manager snap this window against other windows, or special resizing behavior with animations when dragged to the edge of the screen.

edges should either be a single edge, or two adjacent edges (a corner). Other values are not allowed.

Returns true if the operation was supported by the system.

This function was introduced in Qt 5.15.

Reimplements: QSurface::surfaceType() const.

Returns the surface type of the window.

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Override this to handle tablet press, move, and release events (ev).

Proximity enter and leave events are not sent to windows, they are delivered to the application instance.

Override this to handle touch events (ev).

Returns the type of the window.

This returns the part of the window flags that represents whether the window is a dialog, tooltip, popup, regular window, etc.

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Restores the default arrow cursor for this window.

Returns the associated Vulkan instance if any was set, otherwise nullptr.

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Override this to handle mouse wheel or other wheel events (ev).

Returns the window's platform id.

For platforms where this id might be useful, the value returned will uniquely represent the window inside the corresponding screen.

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the screen-occupation state of the window

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This signal is emitted when the windowState changes, either by being set explicitly with setWindowStates(), or automatically when the user clicks one of the titlebar buttons or by other means.

the screen-occupation state of the window

The window can be in a combination of several states. For example, if the window is both minimized and maximized, the window will appear minimized, but clicking on the task bar entry will restore it to the maximized state.

This function was introduced in Qt 5.10.

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